1. Field of the Invention
The invention generally relates to pumps and motors that have a rotor disposed within a stator to give relative rotational movement. More particularly, the invention relates to a reinforced stator insert with a magnetic reinforcing agent that is incorporated into a stator insert.
2. Background of the Technology
Progressive cavity type pumps (PC pumps) and motors generally include a stator having a helical internal bore, having lobes, in which a helical rotor, also having lobes, is positioned and can rotate in. The outer surface of the rotor and the inner surface of the stator are both helical and together create hollow chambers between their contact points in which fluid can travel. During rotation of the rotor, these hollow chambers advance from one end of the stator towards the other end during the rotation of the rotor. Each of these hollow chambers is isolated and sealed from the other chambers. In conventional progressive cavity style pumps and motors, the rotor lobes and stator lobes are disposed in an interference fit, wherein the rotor has one fewer lobe than the stator. Progressive cavity type pumps can be referred to as a PC pump, a progressive cavity pump, a progressing cavity pump, an eccentric screw pump, or a cavity pump.
These PC pumps can be used as a pump to transfer fluids or used as a motor utilizing the fluid passing through the chambers as a power source. The progressive cavity type motors are sometimes referred to as a positive displacement motor (PD motor), a progressive cavity motor, a progressing cavity motor, an eccentric screw motor, or a cavity motor. Because a PD motor design has few components, it can be made with a small diameter while being able to generate considerable torque. In some applications, this design is applied to subsurface boring motors (i.e. mud motors) for the drilling of wellbores. The medium that is pumped or used as the drive fluid may contain a certain amount of particles without the risk of damaging the pump or motor, which is an advantage of utilizing eccentric screw motors in drilling wellbores. Drilling mud that is used to cool and lubricate the drill bit and to bring cuttings to the surface up the annulus area between the drill string and the wellbore may be used as the drive fluid for a cavity motor to provide rotational movement to the bit via hydraulic pressure of the drilling mud. This enables the drilling of directional wellbores, which may be used in performance drilling to increase the power at the drill bit, in operations in which the rotation of the drill string is impractical, and in other applications.
Conventional stators typically include a helical cavity component bonded to an inner surface of tubing (e.g., a steel tube) or housing. The helical cavity component in such conventional stators typically includes an elastomeric component called an elastomeric stator insert that lines the steel tube or housing. This elastomeric stator insert provides a surface having at least some resilience with which to facilitate the interference fit with the rotor. It is the elastomeric stator insert that forms the helical cavity component and contacts the rotor.
Conventionally, stator manufacturers use an injection molding process to form elastomeric stator inserts. The injection molding process requires low viscosity materials that can result in limitations on the stiffness and resilience of the final material. Furthermore, the elastomeric stator insert typically must form a seal with the rotor. During operation, the rotor and stator insert are in constant frictional contact at a plurality of locations. Materials with low stiffness, strength, or resilience may wear quickly, reducing efficiency, power, and life span of the elastomeric stator insert. Substances may be incorporated within an elastomer to alter its mechanical properties. For example, carbon nanotubes (CNT) have been added to an elastomeric stator insert in order to increase the modulus and the stiffness of the stator insert.
Powersection and progressive cavity pumps require an injectible uncured elastomer to fill the long stator tube during injection moulding. Traditionally, once the tube and mould tooling is filled, it is cured in an oven or autoclave. Traditionally, various fibers have not been mixed into polymer(s) due to the fibers' high affinity to bundle to one another thus creating a nonhomogeneously filled elastomer. In some instances, materials, such as the aforementioned carbon nanotubes, have been added to polymer(s) through the use of a modification process known in the art as surface functionalization. Although surface functionalization may provide an effective process for the dispersion of carbon nanotubes in the polymer(s), the modification process typically adds significant economic costs to the manufacture of the stator insert. Such costs may make the use of carbon nanotubes economically unfeasible.
In view of the above, it would be desirable to increase the efficiency, power, and life span of the PC pump or PD motor as well as the strength, hysteretic/dynamic properties, tear resistance and resilience of its components. It would also be desirable to incorporate substances within an elastomeric stator insert of a cavity pump or motor to effectively enhance strength, hysteretic/dynamic properties, tear resistance, resilience, and wear properties throughout the elastomeric stator insert. Additionally, it would be desirable to selectively orient and/or position substances throughout an elastomeric stator insert to achieve a desired property. Furthermore, it would also be desirable to have a rotor and stator insert that would also be cost-effective, yet resilient enough to withstand operating conditions and rigid enough to perform under operating conditions for a longer period of time than currently available.